Hot Air Leveling

In the Hot Air Leveling (HAL) process, the copperpads and plated through holes are being tinned. This surface protection prevent the copper from oxidizing, thereby assuring the solderability of boards that had been stored over some time. In the HAL process, the boards to be tinned are first vertically immersed in a flux bath, and right after in a bath of liquid solder. During the retraction of the board from the solder bath, two hot air knifes blow off any excess solder from the pads and from the plated through holes.